Relaxation volumes of microscopic and mesoscopic irradiation-induced defects in tungsten

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http://hdl.handle.net/10138/318087

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Mason , D R , Duc Nguyen-Manh , Marinica , M-C , Alexander , R , Sand , A E & Dudarev , S L 2019 , ' Relaxation volumes of microscopic and mesoscopic irradiation-induced defects in tungsten ' , Journal of Applied Physics , vol. 126 , no. 7 , 075112 . https://doi.org/10.1063/1.5094852

Title: Relaxation volumes of microscopic and mesoscopic irradiation-induced defects in tungsten
Author: Mason, Daniel R.; Duc Nguyen-Manh,; Marinica, Mihai-Cosmin; Alexander, Rebecca; Sand, Andrea E.; Dudarev, Sergei L.
Contributor: University of Helsinki, Materials Physics
Date: 2019-08-21
Number of pages: 19
Belongs to series: Journal of Applied Physics
ISSN: 0021-8979
URI: http://hdl.handle.net/10138/318087
Abstract: The low-energy structures of irradiation-induced defects in materials have been studied extensively over several decades, as these determine the available modes by which a defect can diffuse or relax, and how the microstructure of an irradiated material evolves as a function of temperature and time. Consequently, many studies concern the relative energies of possible defect structures, and empirical potentials are commonly fitted to or evaluated with respect to these. But recently [S. L. Dudarev et al., Nucl. Fusion 58, 126002 (2018)], we have shown that other parameters of defects not directly related to defect energies, namely, their elastic dipole tensors and relaxation volumes, determine the stresses, strains, and swelling of reactor components under irradiation. These elastic properties of defects have received comparatively little attention. In this study, we compute relaxation volumes of irradiation-induced defects in tungsten using empirical potentials and compare to density functional theory results. Different empirical potentials give different results, but some clear potential-independent trends can be identified. We show that the relaxation volume of a small defect cluster can be predicted to within 10% from its point-defect count. For larger defect clusters, we provide empirical fits as a function of defect cluster size. We demonstrate that the relaxation volume associated with a single primary-damage cascade can be estimated from the primary knock-on atom energy. We conclude that while annihilation of defects invariably reduces the total relaxation volume of the cascade debris, there is still no conclusive verdict about whether coalescence of defects reduces or increases the total relaxation volume. Published under license by AIP Publishing.
Subject: STOCHASTIC CLUSTER DYNAMICS
TOTAL-ENERGY CALCULATIONS
KINETIC MONTE-CARLO
POINT-DEFECTS
SELF-INTERSTITIALS
MOLECULAR-DYNAMICS
RADIATION-DAMAGE
PRODUCTION BIAS
CASCADE DAMAGE
INTERATOMIC POTENTIALS
114 Physical sciences
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